1. Field of the Invention
The invention relates to a fan or blower for a turboshaft engine, such as a turbofan, and is particularly concerned with the reduction or suppression of the vibrations to which the fan blades are subjected.
2. Summary of the Prior Art
Various arrangements have already been proposed for suppressing such vibrations. For example, FR-A-1 263 677 discloses a fan assembly comprising a disc having an axis of rotation and a periphery defining a plurality of teeth spaced evenly apart around said disc and a plurality of recesses of dovetail-shaped cross-section disposed between said teeth, a plurality of blades secured to the periphery of said disc, each of said blades comprising a root having a dovetail shape corresponding to that of said recesses, said root being received in a respective one of said recesses, a stem extending radially outwards from said root, a profiled portion defining the blade proper disposed radially outwards from said stem, and two platforms extending transversely from said stem, one on each side thereof, at the junction between said stem and said profiled portion of the blade, said disc and said blades defining a plurality of spaces, each of said spaces being delimited by the stem and one of said platforms of a first of said blades, the stem and one of said platforms of a second of said blades adjacent said first blade, and the peripheral surface of said tooth disposed between the roots of said first and second blades, and a plurality of flyweights disposed one in each of said spaces such that, under the action of the centrifugal force generated when the disc rotates, the flyweights act on the platforms and/or on the stems of the blades.
It is found, however, that this known solution is, for the most part, generally insufficiently effective as a result of a direct, non-scaled down effect of the flyweights.